Action of interleukin-3 on the proliferation of leukaemic progenitor cells from patients with acute myeloblastic leukaemia.

In the present study, we examined the effects of interleukin-3 (IL-3) on the proliferation of leukaemic progenitor cells from 11 Japanese patients with acute myeloblastic leukaemia (AML), including the effect of its combination with granulocyte/macrophage colony-stimulating factor (GM-CSF) or granulocyte colony-stimulating factor (G-CSF). The results showed that IL-3 sufficiently stimulated the proliferation of AML progenitor cells in almost all the cases examined, and that the stimulation pattern of IL-3 was similar to that of GM-CSF, although different from that of G-CSF. Furthermore, IL-3 worked synergistically with G-CSF, whereas IL-3 and GM-CSF together were less actively synergistic (P < 0.05). These findings suggest the possibility of IL-3/G-CSF/cytosine arabinoside (Ara-C) combination therapy, which may be able to enhance the cytotoxic effect of Ara-C on AML progenitor cells powerfully in a wider range of patients including cases refractory for IL-3/Ara-C combination therapy.